This invention relates to a trim tab actuator for a marine propulsion device and more particularly to an automatic trim tab actuator that may be selectively controlled by the operator so as to provide any of a plurality of selected degrees of automatic control.
It is known in connection with marine outboard drives to employ a trim tab that is supported on the outboard drive and which is pivoted in an opposite direction to the steering direction of the outboard drive so as to create a hydrodynamic force that assists in the steering movement. Although such devices have the advantage of providing assist for steering, they have certain disadvantages. The types of devices proposed for this purpose previously are activated by means of a lost motion connection between the steering device of the outboard drive and the outboard drive. That is, the trim tab is activated in response to a predetermined degree of lost motion between the steering input and the actual steering of the outboard drive. As a result this creates a lag in the activation of the trim tab and further necessitates the incorporation of a lost motion mechanism between the steering and the outboard drive. The use of such a lost motion connection has the disadvantage of permitting the outboard drive to move relative to the steering device and thus the outboard drive may be steered by external forces such as waves or the like which will, of course, cause course deviations.
In addition to the aforenoted disadvantages, the previously proposed trim tab activating systems have permitted only a fixed ratio of trim tab position change with respect to changes in position of the outboard drive or the steering input to the outboard drive. However, the optimum trim tab position for a given input may vary with a wide variety of watercraft conditions.
It is, therefore, a principal object of this invention to provide a trim tab actuator for a marine propulsion device that is operative instantaneously upon the application of a steering input.
It is a further object of this invention to provide a trim tab activator that does not require lost motion in the steering of the outboard drive.
It is a further object of this invention to provide a trim tab activator for an outboard drive that can be selectively tuned to a variety of running conditions.
It is yet another object of this invention to provide an operator controllable trim tab activator that permits any of a wide variety of automatic operations to be employed for the trim tab.